Precision feed mechanism with indicator



Dec. 9, 1969 R. mm: ETAL PRECISION FEED MECHANISM WITH INDICATOR 3 Sheets-Sheet l Filed Jan; 19, 1967 INVENTIOR RALPH E. PRICE KURT H.6EBEL @AM ATTORNEY sms 8-571.

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Dec. 9, 1969 R. 2. PRICE ET AL 3,482,361

PRECISION FEED MECHANISM WITH INDICATOR Jan. 19, 5 sheets sheet 5 fi-"WN INVENTOR RALPH E. PRICE KU T M.GEBEL /f7 ATTOR United States Patent Ofifice 3,482,361 Patented Dec. 9, 1969 Int. Cl. B24b 49/00, 51/00 us. (:1. 51-165 ABSTRACT OF THE DISCLOSURE A feed control mechanism for a machine tool is improved by providing mechanism for automatically stopping the feed of the machine before the end of a machining operation with there being additional fine feed mechanism for effecting a further and final feeding movement of the machine.

11 Claims This application is a substitute for our copending application Ser. No. 409,439, filed Nov. 6, 1964, and entitled Precision Feed Mechanism with Indicator, and now abandoned.

This invention relates to machine tools, particularly grinding machines, and more particularly, to a means for effecting a fine feed movement of a wheel support at or near finished size of a workpiece, and to an indicator for showing the progress or movement of the wheel support during a final feed movement.

The means for effecting a fine feed movement is described in US. Patent No. 3,183,631, granted May 18, 1965. The apparatus disclosed in this patent is a centerless grinder having a manually operated control valve which is mounted at the right hand end of the machine. The indicator for showing the extent of movement of the wheelbase in response to the operation of said valve is also mounted at the right hand end of the bed in a horizontal position and in the path of an actuating member attached to the grinding wheel support.

In order for the operator to control the fine feed, it is necessary to stand at the end of the machine to operate the valve and at the same time, to watch the movement of the wheel support as shown by the indicator. This position on a centerless grinder is not too far away from the normal position of the operator. However, for a centertype grinder, it is inconvenient and time-consuming for the operator to leave the normal operator's position in the front of the machine and go to the rear of the machine to actuate and observe the fine feed movement.

Furthermore, when the work support position is changed for workpieces of different diameters or compensation for wheel wear, it is necessary to reposition the indicator.

It is, therefore, an object of the present invention to provide a fine feed movement of the type in which strain in the feed mechanism combined with a hydraulic stop member is used to effect minute movement of a tool support at a controlled rate not possible with conventional feed mechanisms.

Another object is to provided a control means for the fine feed mechanism convenient to the normal position of the operator.

Another object is to provide an indicator easily readable from the normal position of the operator and preferably at an eye level elevation for showing the movement of the wheel support.

Another object is to provide an indicator which is movable with the wheel support.

Another object is to provide connections between the indicator and wheel support and an abutment on the bed of the machine to actuate the indicator in response to movement of the wheel support.

Another object is to provide an indicator mounting and actuating means which is always ready for operation regardless of changes in position of the wheel support.

FIG. 1 is a hydraulic circuit diagram.

FIG. 2 is an electric circuit diagram.

FIG. 3 shows a partial front elevation of a wheel support showing the apparatus for mounting and actuating an indicator.

FIG. 4 shows a partial right hand end view, partly in section, showing the position of the indicator on the wheel base and the linkage for actuating said indicator.

In FIG. 4, numeral 10 indicates the bed of a grinding machine. Wheel support 15 is slidably mounted on bed 10 as shown in dot and dash outline. Grinding wheel 16 is rotatably mounted in wheel support 15.

The work support in the form of a headstock 20 rotatably supports workpiece W in operative relation to grinding wheel 16.

A visual gage 25 applied to the workpiece shows the progress of a grinding operation.

The means for advancing the grinding wheel 16 toward and from workpiece W consists of a feed screw 30 rotatably and slidably mounted in bed 10 and having a piston portion 31 slidably mounted in cylinder 32 also in bed 10.

Worm wheel 40' is mounted by means of a sliding key 41 on an extension 43 of feed screw 30. Worm wheel 40 is driven by worm gear 45.

The means for rotating worm gear 45 is a ratchet wheel operable in a clockwise direction by pawl 51 and in a counter-clockwise direction by pawl 52. Pawls 51 and 52 are pivotally mounted on plate 55. The means for actuating pawl 51 consists of a piston in cylinder 61 connected to plate 55 by means of link 62. The means for actuating pawl 52 consists of a piston 65 in cylinder 66 and connected to plate 55 by link 67.

The means for advancing and retracting grinding wheel 16 for a grinding operation consists of a hand wheel shaft 70 rotatably mounted in wheel support 15 and having a hand wheel 71 for manually rotating shaft 70. Shaft 70 has a worm gear 75 in operative engagement with worm wheel 76 at one end of vertical shaft 77 also rotatably mounted in wheel support 15. The lower end of shaft 77 has a worm wheel or pinion 78 which engages feed screw 30. Pinion 80 on shaft 70 engages rack 81. Rack 81 is actuated by piston 82 in cylinder 83.

Abutment of wheel support 15 serves to engage a retard piston 91 in cylinder 92 in bed 10. Grinding wheel 16 is mounted on spindle which, in turn, is rotatably supported in wheel support 15. Spindle 100 is driven by a motor (not shown) through belt 101 and pulley 102.

In order to provide visual indication of the movement of wheel support 15 during finish grinding, indicator is attached to vertical member 111 on bracket 112 which is, in turn, attached in a suitable manner to wheel support 15 directly over spindle 100 and pulley 102 and in eye level position. Indicator feeler 115 passes through bracket 112 to engage actuating arm pivotally attached to said bracket 112 by means of spring hinge 121. Screw in vertical member 111 is for resetting arm 120 to keep it within the range of the indicator 110 and the resetting range is limited by the stop nut 131 on top of screw 130. The other end of arm 120 is connected by means of a flat spring 122 with the upper end of arm 125 pivotally mounted on wheel support 15 by means of spring hinge 126.

A movable abutment 135 is mounted for frictional adjustment relative to bed 10. Abutment 135 is in the path of the lower end of arm 125 and is positioned so that the lower end of arm 125 engages said abutment to actuate indicator 110 while workpiece W is still oversize. Bracket 136, attached to wheel support 15, has a stop screw 137 which engages abutment 135 at the end of the retraction of the wheel support 15. Bracket 138 also attached to wheel support 15, has a stop screw 139 which may be adjusted to stop arm 125 after said arm engages abutment 135. The space between screw 139 and arm 125 determines the extent to which said abutment 135 may actuate indicator 110.

OPERATION The operation of this invention is started at the end of the rough grinding feed when feed completion limit switch 7LS is closed by cam 72 on hand wheel 71 to complete a circuit to energize retard relay 11CR.

An ill-PIOCCSS visual or an automatic gage 25 is applied to the work.

Relay contact 11CR1 closes to energize retard solenoid 4 and shifts retard solenoid valve 150 to the left, connecting retard cylinder 92 with fluid from pump P under sixty pounds or other suitable pressure through the precision feed pilot valve 140. The sixty pounds pressure on retard cylinder 92 is suflicient to prevent further movement of wheel support 15.

A portion of this fluid passes through a throttle valve 145 to precision feed valve 151 which is in the deenergized or right hand position and directs this portion of the fluid to exhaust passage 155. This restricted connection to exhaust does not permit the passage of suflicient fluid to interfere with the pressure exerted in retard cylinder 92 to prevent movement of wheel support 15.

At this point, the workpiece W is still oversize and there is a certain amount of strain in the feed mechanism as a result of the force required to hold wheel support 15 against the retard pressure. The lower end of arm 125 is in contact with abutment 135. Indicator 110 is adjusted to show the reduction in diameter required to bring the work to desired size.

The infeed lever 143 is gradually moved to the left to the precision feed position, depressing the pilot valve 140. Notch 142 in valve 140 restricts the flow of pressure fluid through retard valve 150 to retard cylinder 92 to provide a gradual change to a lower pressure. Due to this reduction in flow, the exhaust flow through throttle valve 145 becomes a greater portion of the total flow, and pressure in retard cylidner 92 is reduced in proportion. The strain in the feed mechanism then causes wheel support 15 to advance at a rate in proportion to the lower pressure, and to discharge fluid from the retard cylinder 92 through the energized retard valve 150, throttle valve 145 and the deenergized valve 151 which directs the fluid to exhaust line 155. This provides a more sensitive control of the discharge of fluid from retard cylinder 92 and, therefore, a more sensitive control of the feed mechanism than if the retard cylinder was merely connected directly to an exhaust line.

During the precision feed movement, the operator Watches indicator 110 which shows the amount of movement of wheel support 15. He also watches the in-process gage 25 on workpiece W to observe the condition of the workpiece as to size and ronndness. The operator controls the advance of grinding wheel 16 by operation of pilot valve 140 to gradually remove any out of round and then controls the final feed to size at a rate which will avoid introducing a further out of round condition on workpiece W until final size is reached as shown by gage 25.

If there is not suflicient strain in the feed mechanism to advance to finished size, infeed lever 143 is moved to the Wheelbase In position, actuating Wheelbase In limit switch 4LS which completes a circuit to energize relay 2CR.

Relay contact 2CR1 closes to complete a circuit from previously closed feed completion limit switch 7L5 to energize precision feed relay 10CR.

Relay contact 10CR1 and 10CR2 complete a circuit .4 to energize precision feed solenoid 3, shifting valve 151 to the left and connecting retard cylinder 92 with fluid under thirty pounds pressure. This is sufiicient to hold wheel supoprt 15 against further movement.

Relay contact 10CR3 closes in a circuit through normally closed timing contacts 2TR1 and 3TR1 to energize relay 15CR.

Relay contact 15CR1 closes to complete a circuit from relay contact 10CR1 through normally closed timing contact 2TR1 to energize timer relays 2TR and 3TR.

Relay contact 15CR2 closes in a circuit parallel to normally closed contact 2TR1.

Normally closed contacts 2TR1 and 3TR1 open and close alternately to provide intermittent energization of relay 15CR.

Relay contact 15CR3 opens and closes intermittently to provide intermittent operation of increment feed relay 16CR.

Relay contact 16CR1 actuates the increment feed solenoid 6 to shift increment feed valve 160 to direct fluid to the cylinder 61 to turn feed screw 30 and reintroduce strain into the feed mechanism.

Infeed lever 143 is returned to neutral position to permit a round-out grinding operation on workpiece W and also to open limit switch 4LS, deenergizing relay 2CR, opening relay contact 2CR1 and deenergizing the relay 10CR, permitting valve 151 to return to the right. With infeed lever 143 in neutral position, valve and notch 142 in valve 140, reconnects the sixty pounds per square inch supply of fluid to retard cylinder 92, thereby maintaining the strain in the feed mechanism.

Infeed lever 143 is then moved to the precision feed position, depressing valve 140 and gradually reducing the flow of the sixty pounds fluid pressure to retard cylinder 92. As the flow of fluid under pressure to retard cylinder 92 is reduced, the discharge of fluid through throttle valve 145 becomes a greater factor in the pressure in retard cylinder 92.

Retard cylinder 92 is connected through the retard valve and the valve 151 which is in its right hand position, to direct fluid from the retard cylinder 92 through throttle valve 145 and to exhaust line 155.

This permits the strain in the feed mechanism to advance the wheel support 15 the remaining amount to bring workpiece W to size. This amount is observed by the operator on indicator 110 so that he can stop the advance movement, when the desired amount of advance takes place and the inprocess gage 25 indicates final size.

We claim:

1. In a feed control mechanism for a machine tool having:

(a) a bed,

(b) a tool support slidably mounted on said bed,

(c) a work support,

(d) a cutting tool mounted on said tool support,

(e) a feed mechanism for advancing and retracting said tool support relative to said work support,

(f) a piston and cylinder adapted to be moved relative to one another by movement of said tool support,

(g) a supply of fluid under pressure,

(h) a valve operable before the end of a machining operation for directing said fluid under pressure to said cylinder to stop the advance of said tool support,

(i) power means to actuate said feed mechanism while said tool support is held against movement by the pressure in said cylinder to place said feed mechanism under strain,

(j) means to reduce the pressure in said cylinder until it is overcome by the strain in said feed mechanism to cause the discharge of fluid from said cylinder and the corresponding movement of said tool support,

(k) and a single control lever remotely located with respect to said piston and cylinder and said feed mechanism and operable to selectively operate said valve and said power means.

2. In a feed control mechanism for a machine tool having:

(a) a bed,

(b) a tool support slidably mounted on said bed,

(c) a work support,

(d) a cutting tool mounted on said tool support,

(e) a feed mechanism for advancing and retracting said tool support relative to said work support,

(f) a piston and cylinder adapted to be moved relative to one another by movement of said tool support,

(g) a supply of fluid under pressure,

(h) a valve operable before the end of a machining operation for directing said fluid under pressure to said cylinder to stop the advance of said tool sup- P (i) power means to actuate said feed mechanism while said tool support is held against movement by the pressure in said cylinder to place said feed mechanism under strain,

(j) means to reduce the pressure in said cylinder until it is overcome by the strain in said feed mechanism to cause the discharge of fluid from said cylinder and the corresponding movement of said tool sup port,

(k) and a visual indicator in eye level position on said tool support for showing both the movement of said tool support upon said release of strain in said feed mechanism and when final size is reached.

3. Apparatus of claim 2 together with:

(a) means for actuating said visual indicator comprising actuating means on said bed and a linkage on said tool support, one end of which is in operative relation to said visual indicator, the other end of which is in position to engage said actuating means in response to movement of said tool support.

4. In a feed control mechanism for a machine tool having:

(a) a bed,

(b) a tool support slidably mounted on said bed,

(c) a work support,

(d) a cutting tool mounted on said tool support,

(e) a feed mechanism for advancing and retracting said tool support relative to said work support,

(f) a piston and cylinder adapted to be moved relative to one another by movement of said tool support,

(g) a supply of fluid under pressure,

(h) a valve operable before the end of a machining operation for directing said fluid under pressure to said cylinder to stop the advance of said tool support,

(i) power means to actuate said feed mechanism while said tool support is held against movement by the pressure in said cylinder to place said feed mechanism under strain,

(j) means to reduce the pressure in said cylinder until it is overcome by the strain in said feed mechanism to cause the discharge of fluid from said cylinder and the corresponding movement of said tool support,

(k) said means for reducing the pressure in said cylinder including,

(1) an exhaust line,

(In) a restriction in said exhaust line,

(11) and means to connect said cylinder to said exhaust line.

5. In a feed control mechanism for a machine tool having:

(a) a bed,

(b) a tool support slidably mounted on said bed,

(0) a work support,

(d) a cutting tool mounted on said tool support,

(e) a feed mechanism for advancing and retracting said tool support relative to said work support,

(f) a piston and cylinder adapted to be moved relative to one another by movement of said tool support,

(g) a supply of fluid under pressure,

(h) a valve operable before the end of a machining operation for directing said fluid under pressure to said cylinder to stop the advance of said tool sup- (i) power means to actuate said feed mechanism while said tool support is held against movement by the pressure in said cylinder to place said feed mechanism under strain,

(j) means to reduce the pressure in said cylinder until it is overcome by the strain in said feed mechanism to cause the discharge of fluid from said cylinder and the corresponding movement of said tool support,

(k) said means for reducing the pressure in said cylinder including (1) another valve connected to said supply of fluid under pressure and normally positioned to direct said fluid to exhaust,

(m) a restriction in the connection between said fluid supply and said another valve to prevent a drop in pressure in said cylinder,

(11) and means to reduce the flow of fluid to the first mentioned valve until said fluid exerts a force on said piston less than that exerted by the strain in said feed mechanism.

6. In a machine tool:

(a) a bed,

(b) a tool support slidably mounted on said bed,

(0) feeding means for moving said tool support by small increments,

(d) an indicator on said tool support to show said tool support movement,

(e) an actuating means for said indicator pivotally mounted on said tool support and having (f) a portion in operative relation to said indicator,

(g) an adjustable abutment on said bed,

(h) and another portion of said actuating means in position to engage said abutment,

(i) said actuating means including (k) a first actuating arm,

(1) a spring hinge for supporting said first actuating arm,

(m) a second actuating arm supported on a second spring hinge,

(11) said first and second actuating arms being those portions of said actuating means mounted on said tool support,

(0) a flat spring connection between a lower end of said first actuating arm and an upper end of said second actuating arm,

(p) and a lower end of said second actuating arm being that portion of said actuating means in position to engage said abutment.

7. Apparatus of claim 4 in which said means for reducing the pressure in said cylinder also includes:

manually actuated remote control means for alternately actuating said power means and said means to connect said cylinder with said exhaust line.

8. In a machine tool,

(a) a bed,

(b) a tool support slidably mounted on said bed,

(c) feeding means for moving said tool support by small increments,

(d) an abutment on said bed,

(e) an indicator on said tool support in eye level position and remote from said abutment to show said tool support movement,

(f) an actuating means for said indicator pivotally mounted on said tool support and having (g) a portion in operative relation to said indicator,

(h) and another portion of said actuating means in position to engage said abutment.

9. In a feed control mechanism for a machine tool having:

(a) a bed,

(b) a tool support slidably mounted on said bed,

() a work support,

(d) a cutting tool mounted on said tool support,

(e) a feed mechanism for advancing and retracting said tool support relative to said work support,

(f) a piston and cylinder adapted to be moved relative to one another by movement of said tool sup- P (g) a supply of fluid under pressure,

(h) a valve operable before the end of a machining operation for directing said fluid under pressure to said cylinder to stop the advance of said tool support,

(i) power means to actuate said feed mechanism while said tool support is held against movement by the pressure in said cylinder to place said feed mechanism under strain,

(j) and control means including a lever remotely located with respect to said piston and cylinder and said feed mechanism,

(k) a valve means operable by said lever in one position for reducing the pressure in said cylinder until said pressure is overcome by the strain in said feed mechanism for advancing said tool support at a controlled rate,

(1) and means operable by said lever in another position for applying a blocking pressure to said cylinder and for initiating operation of said power means for actuating said feed mechanism to again place said feed mechanism under strain in preparation for further advance of said tool support.

10. In a feed control mechanism for a machine tool having a bed, a tool support slidably mounted on said bed, a Work support, a cutting tool mounted on said tool support, feed mechanism for advancing and retracting said tool support relative to said work support, a piston and cylinder attached to said tool support, a positive stop in the path of said piston, a supply of fluid under pressure connected to said cylinder, power means to advance said feed mechanism while said tool support is held against movement by said positive stop and the pressure in said cylinder, and control means including a lever remotely located with respect to said piston and cylinder and said feed mechanism, a valve means operable by said lever in one position for reducing the pressure in said cylinder until said pressure is overcome by the strain in said feed mechanism for advancing said tool support at a controlled rate, and means operable by said lever in another position for applying a blocking pressure to said cylinder and for initiating operation of said power means for actuating said feed mechanism to again place said feed mechanism under strain in preparation for further advance of said tool support.

11. A grinding machine comprising a bed, a grinding wheel support slidably mounted on said bed, a work support, a grinding wheel rotatably mounted on said wheel support, feed mechanism for advancing and retracting said wheel support relative to a workpiece, power means for advancing said feed mechanism, means to stop the movement of said wheel support comprising a piston and cylinder attached to said Wheel support, means to maintain pressure in said cylinder sufficient to stop or prevent movement of said Wheel support, and control means including a lever remotely located with respect to said piston and cylinder and said feed mechanism, a valve means operable by said lever in one position for reducing the pressure in said cylinder until said pressure is overcome by the strain in said feed mechanism for advancing said tool support at a controlled rate, and means operable by said lever in another position for applying a blocking pressure to said cylinder and for initiating operation of said power means for actuating said feed mechanism to again place said feed mechanism under strain in preparation for further advance of said wheel support.

References Cited UNITED STATES PATENTS 1,290,434 1/ 1919 Walter 33l47 3,019,565 2/1962 Hatstat et a1. 51165 3,183,631 5/1965 Price et al. 5l-165 LESTER M. SWINGLE, Primary Examiner 

